A research team from the National University of Singapore (NUS) has successfully turned tofu whey, a liquid that is generated from the production of tofu and is often discarded, into a tasty alcoholic beverage, which they named Sachi. The innovative fermentation technique also enriches the drink with isoflavones, which are antioxidants that have many health benefits.

The creation of Sachi was initiated a year ago by Liu Shao Quan, associate professor, food science and technology programme, faculty of science, NUS, and Chua Jian Yong, his Ph D student, who have an interest in sustainable food production.

“The traditional way of manufacturing tofu produces a large amount of whey, which contains high levels of calcium and unique soy nutrients, such as isoflavones and prebiotics,” said Chua.

“Hence, disposing tofu whey is wasteful. Very little research has been done to transform tofu whey into edible food and beverage products,” he added.

“I had previously worked on alcohol fermentation during my undergraduate studies at NUS, so I decided to take up the challenge of producing an alcoholic beverage using the whey. The drink turned out to be tasty, which is a pleasant surprise,” said Chua.

Turning waste into a beverageTofu, also known as bean curd, is a popular food made from soybean. One of the most common methods of producing tofu is by curdling freshly-boiled soy milk, cooling it, and pressing it into a solid block.

During the pressing process to remove excess water, tofu whey is generated. However, when tofu whey is discarded as an untreated waste, it creates environmental pollution, as the protein and soluble sugars in the whey could contribute to oxygen depletion in the waterways.

In contrast, upcycling tofu whey can be a means of generating economic returns for businesses.

“As a result, the amount of tofu whey has also increased proportionally. Alcoholic fermentation can serve as an alternative method to convert tofu whey into food products that can be consumed directly,” he added.

“Our unique fermentation technique also serves as a zero-waste solution to the serious issue of tofu whey disposal,” stated Liu.

Under Liu’s guidance, Chua took about three months to come up with a unique recipe to make an alcoholic beverage from tofu whey.

He first made fresh soy milk from soybeans, and then used it to make tofu. In the course of making tofu, he collected the whey.

Sugar, acid and yeast were added to the tofu whey, and the concoction was fermented to produce the alcoholic beverage.

Chua also designed a novel fermentation technique which utilises the tofu whey fully, without generating any waste. The whole process of making the alcoholic beverage took about three weeks.

Biotransformation of tofu whey yields benefitsAltering the composition of tofu whey via biotransformation methods converted its strong beany odour into a fruity, sweet flavour, and extended the shelf life of tofu whey from less than a day to about four months.

In addition, after fermentation, the bound isoflavones that were present in the tofu whey were transformed into free isoflavones that can be absorbed more easily by the human body.

The result is a refreshing beverage that is a tad sweet, with fruity and floral notes, and has an alcohol content of about 7-8 per cent.

The team has filed a patent for the novel process of making Sachi, and they are looking to collaborate with industry partners to introduce the drink to consumers.